The use of digitally signed certificates is well known in the art.
Consider the following example: Two entities A and B each have asymmetric key pairs, each key pair comprising a public key and a private key, as is well known in the art. Entity A is to sign a certificate for entity B, the certificate comprising the public key of entity B and other data regarding entity B.
The widespread and well known X.509 format is typically used in the prior art for the purpose of producing certificates of the type described above. The X.509 format is defined in ITU-T Recommendation for X.509, published March 2000, available from ITU-T (the International Telecommunication Union Standardization Sector).
The disclosures of all references mentioned above and throughout the present specification are hereby incorporated herein by reference.